This invention relates generally to an apparatus and method for cleaning debris from a permeable support surface. It is specifically directed toward cleaning debris from between bristles that form the surface of a bristle bed cutting table.
Bristle bed support surfaces have become commonplace in the garment industry. Typically, vacuum is applied from underneath a bristle bed support surface to positively hold down a lay-up of sheet material upon which a cutter operates. The cutter usually employs a high speed reciprocating blade. The blade cuts through every ply of the lay-up by penetrating through the surface of the bristle bed upon which the lay-up rests. Free ends of the bristles support the lay-up, while a vacuum permeates between the bristles from under the bristle bed and maintains the sheet material in place so cutting operations can be performed thereon. Improvements in bristle beds have led to provisions for at least an endless conveyorized belt of bristle blocks that is movable in a longitudinal direction.
Although improving the cutting operation, the essential gaps between individual bristles and between blocks of bristles tend to trap drill slugs, lint and other debris generated by the cutting process. The hold-down vacuum created in the bed exacerbates this adverse consequence, as the accumulating debris constricts vacuum ports and diminishes the strength and uniformity of the vacuum within the bristle bed so that the sheet material may not be uniformly held in place. This inevitably results in increased error rates due to shifting sheet material. Accumulated debris tends to become impacted between individual bristles, restricting their ability to flex and making them more susceptible to be cut by the blade during normal use. Cleaning this debris is therefore essential to maximizing the operational efficiency of such cutting machines and to extend bristle life.
Thoroughly cleaning bristle beds has historically been a time consuming and labor intensive process. Two types of bristle beds predominate: non-conveyorized bristle beds, and conveyorized bristle beds wherein at least a portion of the bed comprises an endless movable conveyor.
A rake at the take-off end of a conveyorized bristle bed to agitate the bristles in conjunction with a vacuum chamber having openings to suck debris away from the bristles have been employed to remove debris. A lip adjacent to a cleaning vacuum port slightly parts or xe2x80x98rifflesxe2x80x99 the bristle free ends, extending the vacuum""s reach deeper into the mat. Prior art embodiments perform well within certain parameters, but generally fail to draw out deeply embedded debris. Some operate against gravity and are therefore self-limiting. All of the prior art methods fail to reach debris deep within the bristle bed, and fail to dislodge much of the debris that is entrained by nicks and barbs on the bristles. These nicks and barbs are unavoidably created when the cutter blade penetrates into the bristle bed and nicks the sides of the bristles. Debris clings to these barbs, reducing the effectiveness of prior art cleaning devices.
The debris not removed by the above prior art devices is retained and drawn deeper by the hold-down vacuum itself. If debris is not efficiently cleaned within the first few cleaning cycles, it likely remains embedded within the bristle bed until removed when the cutting table is taken out of service for major cleaning. Retained debris degrades both vacuum strength at the support surface, vacuum uniformity across that surface, and degrades bristle life. Since this debris accumulates, each marginal increase in the efficiency of debris removal results in a marked increase in the time interval between major cleanings of the bristle bed, less machine down time and more productivity per cycle or shift.
Based on the foregoing, it is the general object of the present invention to provide a bristle bed cleaner and method of use that overcomes the problems and drawbacks of prior art cleaners and methods.
In accordance with the present invention, a sheet material cutting machine having at least one endless belt conveyor is provided. The conveyor defines at least a portion of a bristle bed that includes moveable bristles that define a support surface for sheet material when the bristle free ends extend upwards. Opposite the bristle free ends are bristle root ends, that may be fixedly attached to bristle blocks. A bristle cleaning station is located adjacent to downward extending bristles on the return run of the conveyor for removing debris from between the bristles. The cleaning station comprises a plurality of air jets to direct pressurized air upwardly toward the bristle root ends and a vacuum inlet chamber adjacent to the air jets to draw out and carry away any debris dislodged from between the bristles. The air jets may also be used to extract impacted debris from between downwardly extending bristles.
A method is also disclosed to most effectively use the cleaner means of the present invention. First, the bristle bed is inverted so that the bristles on that segment to be cleaned extend downward. On a conveyorized bed, this occurs on the return run of the conveyor where the free ends of the bristles to be cleaned lie below the root ends. The second step is optional; the downwardly extending bristles are separated or riffled to define an enlarged space between several of the bristles. Third, pressurized air is directed toward the enlarged space to dislodge debris accumulated between the bristles. This pressurized air may also be used to remove impacted debris from the bristles. Finally, a vacuum is created adjacent to the bristle bed near the enlarged space to draw away the dislodged and/or removed debris.